JPS6221954Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a pyroelectric infrared detector used in various infrared sensors or infrared thermometers.

As infrared detectors, photon infrared detectors and thermal infrared detectors are widely known. A photon-type infrared detector is a method of directly converting infrared photon energy into electricity, and is constructed of PBS, H _g C _{d Te,} or the like. On the other hand, thermal infrared detectors use infrared rays as a heat source and detect changes in the temperature of the element due to the heat generation effect. Typical examples include bolometers and Golay cells. The present invention relates to an improvement of a pyroelectric infrared detector that belongs to the latter category of thermal infrared detectors.

In general, the sensitivity R _v of a pyroelectric infrared detector is expressed by the following equation (1).

However, V: Output voltage Iω: Incident infrared rays η: Emissivity ω: Angular frequency (=2π) A: Effective area of element R: Input resistance G: Thermal radiation τT: Thermal time constant τE: Electrical time constant dp _s / d _T : Pyroelectric coefficient C: Volume specific heat Since a pyroelectric infrared detector is a heat detector,
The sensitivity R _V depends on the heat capacity of the element. Heat capacity is determined by specific heat and volume, and since specific heat is a constant specific to the material, structurally the sensitivity R _V depends on the volume of the element. The volume is determined by the area A and the plate thickness.
As the area A increases, the rise response determined by the thermal time constant τ _T becomes slower, and the sensitivity R _V decreases.
Even if the entire area is hit by incident infrared rays, the signal output voltage V
is R _V ·Iω, so there is no area dependence.
After all, the sensitivity R _V is inversely proportional to the plate thickness of the element, so the thinner the plate thickness is, the better the sensitivity R _V is. For this reason, conventionally, pyroelectric elements for infrared detection, for example, 2×2×
An extremely thin and small device of about 0.05 ^t (mm) was used.

As mentioned above, this type of pyroelectric element is very thin, so in order to operate stably, it is necessary to fix it to a support stand or the like for reinforcement. In this case, if the heat applied to the pyroelectric element due to the thermal effect of infrared rays is dissipated through the support base, the thermal effect on the element will not work effectively, resulting in a decrease in the sensitivity R _V of the detector. If the heat capacity of the support base is too large compared to the heat capacity of the pyroelectric element, the response of the pyroelectric element to rapid intermittent fluctuations in infrared rays will be slow due to the heat dissipation and heat storage effects of the support base, and the response of the detector will be reduced. This causes problems such as a decrease in temporality. As a technical means to solve these problems, support structures as shown in FIGS. 1 to 4 have conventionally been used.

First, in the conventional example shown in FIG.
Connect and fix the wire 2 to one side of the
One end of the pyroelectric element 1 is tied to a lead terminal 4 implanted in the bottom plate 3 and fixed by soldering, so that the pyroelectric element 1 is suspended from the bottom plate 3, which has a large heat dissipation and heat storage function. Electrodes 1 provided on both sides of the pyroelectric element 1
Of the electrodes a and 1b, the front electrode 1a is electrically connected to a lead terminal 6 through a lead wire 5, and the electrode 1b is electrically connected to a lead terminal 4 using the wire 2 as a lead wire. Further, when the bottom plate 3 is made of a metal plate material or the like, the lead terminal 6 for electrically connecting the electrode 1a is connected to the bottom plate 3 through an insulator 7 such as insulating glass.
to be planted. Note that 8 is a lid that constitutes an exterior case together with the bottom plate 3, and an infrared entrance window 9 is provided in the center of the lid.

However, the conventional example shown in FIG.
It requires a complicated and troublesome process of fixing the pyroelectric elements 1, which are processed to be ultra-thin with approximately 50 μm, onto the wire 2 one by one, which makes the installation work difficult, lacks mass productivity, and increases costs. There is a drawback. Also,
The support surface of the pyroelectric element 1 is small, leading to insufficient support strength and tilting of the pyroelectric element 1, which tends to make the support unstable, and the mechanical strength is low, making it vulnerable to vibrations and shocks. There were also some shortcomings.

Next, in the conventional example shown in FIG. 2, an insulating base 10 made of quartz or the like is fixed on the bottom plate 3 by adhesive or other means, and one side of the pyroelectric element 1 is fixed on the insulating base 10 by adhesive. It has a structure.

Although this conventional example has advantages such as high support stability of the pyroelectric element 1, high mechanical strength, and resistance to vibration and shock, one electrode of the pyroelectric element 1
Since the electrodes 1b are fixed to the insulating base 10 in contact with each other, there is a drawback that it becomes difficult to lead out the electrode 1b.

Next, in the conventional example shown in FIG. It has a structure in which one side of the pyroelectric element 1 is fixed with adhesive.

In the case of this conventional example, there is an advantage that an insulating base 11 with small heat dissipation and heat storage effects can be used, but an ultra-thin pyroelectric element 1 of around 50 μm is placed on the insulating base 11.
This method has drawbacks such as difficult attachment work, lack of mass productivity, high cost, and difficulty in leading out the electrode 1b as in the case of FIG. 2.

Next, the conventional example shown in FIG. 4 has a structure in which a metal base 12 is fixed onto a bottom plate 3 by means of adhesion or the like, and one side of a pyroelectric element 1 is adhesively fixed onto this metal base 12 using a conductive adhesive or the like.

This conventional example has the advantage that the electrode 1b can be easily derived, but since the metal base 12 is used, the heat dissipation is high, the low frequency response is not particularly good, and the pyroelectric element 1 is In contrast to single crystal or polycrystalline ceramics, the base 12 is made of metal, so it cannot be cut with the same blade, making manufacturing, processing and assembly troublesome, and lacks mass productivity. Therefore, disadvantages such as difficulty in processing the base 12 to improve heat insulation are inevitable.

The present invention eliminates the above-mentioned conventional drawbacks, has high support stability for the pyroelectric element, has high mechanical strength, is resistant to vibrations and shocks, has excellent low frequency response, and has the ability to derive and manufacture electrodes. The purpose of the present invention is to provide a highly reliable and inexpensive infrared detector that is easy to process and assemble, and is suitable for mass production.

In order to achieve the above object, an infrared detector according to the present invention is characterized in that a pyroelectric element is mounted on a base made of an oxide sintered body whose element body itself is conductive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be specifically described below with reference to the accompanying drawings which are examples. FIG. 5 is a front sectional view of the infrared detector according to the present invention. In the figures, the same reference numerals as in FIGS. 1 to 4 indicate the same components.

In this embodiment, a base 14 made of a conductive sintered body is fixed on the bottom plate 4 by adhesive or other means, and electrodes 1a are placed on both sides of the conductive sintered body base 14 in the thickness direction. , 1b of the pyroelectric element are fixed on a surface using a conductive adhesive. The conductive sintered body constituting the base 14 is made of an oxide sintered body such as conductive ferrite, and the element body itself has conductivity.

As described above, the base 14 is made of a conductive oxide sintered body, and the pyroelectric element 1 is attached to the base 14.
If the structure is such that it is installed, the following effects can be obtained.

(a) Since the base 14 serves as a lead conductor for the electrode 1b on the back surface, it becomes very easy to lead out the electrode 1b. For example, a structure in which a lead wire 15 or the like is connected to the bottom plate 3 and the lead wire 15 to the lead terminal 4 is used, and the electrode 1b is not provided with a conductive film on the surface of the base 14.
can be electrically connected to the lead terminal 4 via the base 14.

(b) Since both the pyroelectric element 1 and the base 14 that supports it are sintered bodies, they can be cut in the same process using the same cutting tool. Therefore, mass productivity is improved.

(c) Since the base 14 is a sintered body of oxide such as conductive ferrite, it has high heat insulation properties. Moreover, this oxide sintered body itself has conductivity, and there is no need to form a metal conductive film or the like on the surface of the base 14 that reduces the heat insulation effect. Therefore, the heat insulation properties are improved, and the response at low frequencies is improved.

(d) Since the base 14 is a sintered body, it is easy to devise ways to improve the heat insulation properties. For example, if a groove 16 is provided on the surface on which the pyroelectric element 1 is attached, as shown in FIG. 6, or a through hole 17 is provided as shown in FIG. 7, to improve heat insulation, it is necessary to Can be formed all at once.

(e) Since the base 14 is a conductive sintered body, polishing of the base 14 is easy. This greatly facilitates the work of adjusting the viewing angle by polishing the base 14 to adjust its height.
Moreover, since the element body itself is a sintered body having conductivity, no matter where the polished surface is placed, the polished surface always becomes a conductive surface, and the pyroelectric element 1 can be brought into direct contact with each other for conduction. Therefore, the viewing angle can be set to a highly accurate value determined by the polishing position.

(f) Since the pyroelectric element 1 can be mounted closely on the base 14, an infrared detector with high support stability, high mechanical strength, and resistance to vibration and shock can be realized. can.

As explained in detail above, the infrared detector according to the present invention is characterized in that the pyroelectric element is mounted on a base made of an oxide sintered body that itself has conductivity, so that the infrared detector according to the present invention is The support stability of the body element is high,
We provide a highly reliable and inexpensive infrared detector that has high mechanical strength, is resistant to vibrations and shocks, has excellent low frequency response, and is easy to derive electrodes, manufacture, process, and assemble, and is highly suitable for mass production. can do.

[Brief explanation of the drawing]

1 to 4 are front sectional views of different examples of conventional infrared detectors, FIG. 5 is a front sectional view of an infrared detector according to the present invention, and FIGS. 6 and 7 are different examples of the base. It is each perspective view which shows the Example. 1... Pyroelectric element, 1a, 1b... Electrode, 14
... Conductive sintered body, 16 ... Groove, 17 ... Through hole.

Claims (1)

[Claims for Utility Model Registration] (1) An infrared detector characterized in that a pyroelectric element is mounted on a base made of an oxide sintered body that itself has conductivity. (2) The infrared detector according to claim 1, wherein the base has one or more holes. (3) The infrared detector according to claim 1, wherein the base has one or more grooves. (4) The infrared detector according to claim 1, 2, or 3, wherein the pyroelectric element and the base are connected and fixed using a conductive adhesive. . (5) Claim 1 of the utility model registration claim, characterized in that the base is made of conductive ferrite;
The infrared detector according to item 2, 3 or 4.